The present invention is directed to pump driving mechanisms, and particularly variable speed mechanisms for driving vertical pumps.
A variety of mechanisms for driving pumps are known. For example, Hans Jaggi in U.S. Pat. No. 3,873,244 describes an electric variable-speed drive comprising a hollow shaft electric motor with a hydrodynamic transmission unit above the motor as an integral machine. The variable speed mechanism is desirable so that the speed of the pump can be controlled independently of the speed of the motor. By such independent control, energy is not wasted by operating the pump at a higher speed than is required for a given situation.
Although the pump drive mechanism shown by Jaggi is useful for many applications, such as sewage and waste water pumps, it is of limited use in deep well applications. This is because in deep well applications such as in geothermal wells, it is difficult to determine the necessary length for the pump shaft due to variations in the threaded column pipe makeup and due to changes in the column pipe length from expansion and contraction with temperature changes. By thermal expansion, a pump shaft in a geothermal well can increase in length by as much as four inches. The Jaggi mechanism provides no mechanism for dealing with these changes.
Another problem with the Jaggi mechanism is that it is a complete unit comprising a motor and a hydrodynamic transmission unit of unitized construction. It would be difficult to adapt the Jaggi unit for retrofitting existing motors and pumps so that they can be supplied with a variable speed transmission unit. For example, to so use the Jaggi unit would necessitate discarding the Jaggi motor.
Mechanisms for vertically adjusting a pump shaft while retaining the motor in a vertical position are known. For example, M. E. Layne in U.S. Pat. No. 1,715,401 describes such a mechanism. However, adaptation of the Jaggi drive mechanism for vertical adjusting of the pump shaft is not readily accomplished.
In view of the foregoing, it is evident there is a need for a pump driving mechanism which can be retrofitted to existing pump and motor installations, where the pump driving mechanism includes a variable speed transmission unit and means for vertical adjustment of the pump shaft.